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41.6 Gb/s RZ-DPSK to NRZ-DPSK Format Conversion in a Microring Resonator
No full textRZ-DPSK to NRZ-DPSK format conversion in a silicon microring resonator is demonstrated experimentally for the first time at 41.6 Gb/s. The converted signal eye diagrams and bit-error-rate measurements show the good performance of the scheme
Properties of Rigid Polyurethane Foams Filled with Chopped Glass Fibers
No full textProperties of spray-applied rigid polyurethane foam filled with chopped glass fibers 4 mm long are investigated. Effects of filler content (3 – 18 wt. %) on modulus of elasticity and strength of filled foam at tension and compression are estimated. An increase in modulus of elasticity in the transverse direction up to 20% with increasing content of chopped glass fibers is observed. The strength of filled polyurethane foams decreased or was unchanged at loading of chopped glass fibers. Cellular structure, as well as failure mode of filled foams at tension is analysed
Usage of Graph Patterns for Concept Map Extension
No full textIn concept map-based assessment an expert’s concept map can be expanded using graph patterns to add hidden and inverse relations. This helps to avoid forcing a learner to use certain structures and names. Graph patterns are subgraphs that describe combinations of concept map elements, from which extra relations can be inferred. In this paper an enriched set of graph patterns is described along with their respective IF...THEN rules which can be used for automated knowledge assessment. Some of them are already implemented in the intelligent and adaptive knowledge assessment system IKAS
Molecular and Crystal Structure of Sildenafil Base
No full textSildenafil citrate monohydrate, well known as Viagra®, is a drug for the treatment of erectile dysfunction. Here we present the X-ray crystal structure of the sildenafil base, C22H30N6O4S. The compound crystallizes in the monoclinic system, space group P21/c with the unit cell parameters a = 17.273(1), b=17.0710(8), c=8.3171(4) A° , β =99.326(2), Z = 4, V = 2420.0(3) A° 3. A comparison with the known crystal structures of sildenafil citrate monohydrate and sildenafil saccharinate is also presented
Monoclinic Polymorph of 3,7-dimethyl-1- (5-oxohexyl)-3,7-dihydro-1H-purine-2,6- dione
No full textThe structure of the title compound, pentoxifylline, C13H18N4O3, has been previously characterized as a triclinic polymorph [Pavelcik et al. (1989). Acta Cryst. C45, 836–837]. We have discovered the monoclinic form. There are no strong hydrogen bonds in the crystal structure, rather, moderate C— H...O hydrogen bonds are present, which serve to stabilize the three-dimensional architectur
Experimental Evaluation of the Hardness and Elastic Properties of Wear-Resistant Nonstructural Ion-Plasma Coatings by Nanoindentation
No full textExperimental Evaluation of the Hardness and Elastic Properties of Wear-Resistant Nonstructural Ion-Plasma Coatings by Nanoindentatio
Impact of Composite Component of Aircraft and Its Damage
No full textImpact of Composite Component of Aircraft and Its Damag
Multicomponent Pharmaceutical Cocrystals: Furosemide and Pentoxifylline
No full textThe design and synthesis of stable solid-state pharmaceutical cocrystals of diuretic drug furosemide and peripheral blood flow improving agent pentoxifylline have been performed during present research. Single crystals suitable for X-ray structure analysis for furosemide-pentoxifylline cocrystal, its hydrate and acetone solvate forms have been obtained. In all three crystal structures there are two intramolecular hydrogen bonds in furosemide molecules. A number of intermolecular hydrogen bonds type NH⋅⋅⋅O, OH⋅⋅⋅O and OH⋅⋅⋅N are present in all three structures, which serve to stabilize the three-dimensional architecture.
The furosemide-pentoxifylline (1:1) cocrystal I crystallizes in a monoclinic system, space group P21/c and cell parameters are: a = 8.0948(2), b = 9.3747(2), c = 36.291(1), β = 93.128(2), V = 2749.89 Ǻ3, R = 6.98 %.
The furosemide-pentoxifylline-water (1:1:1) cocrystal II crystallizes in a triclinic system, space group P-1 and cell parameters are: a = 8.4052(2), b = 9.4494(3), c = 19.6748(9), α = 92.649(1), β = 99.170(2), γ = 111.466(1), V = 1426.35 Ǻ3, R = 7.95 %. The water molecule participates in the stabilization of crystal structure by means of strong hydrogen bonds type OH⋅⋅⋅O between carbonyl group’s oxygen atoms O24 and O36 of pentoxifylline molecules and form chains along crystallographic axis b.
The furosemide-pentoxifylline-acetone (1:1:1) cocrystal III crystallizes in a triclinic system, space group P-1 and cell parameters are: a = 9.3099(2), b = 9.5317(3), c = 19.2653(7), α = 99.733(2), β = 96.057(2), γ = 109.197(3), V = 1567.27 Ǻ3, R = 6.27 %. Moderate NH⋅⋅⋅O type hydrogen bond connects nitrogen of amino group of furosemide with oxygen of carbonyl group of acetone
Определение модуля упругости полимерных материалов на тонкостенных цилиндрических образцах
No full textРазработана методика определения модуля упругости полимерного материала на основе экспериментальных диаграм сжатия и растяжения тонкостенных круговых оболочек в геометрически нелинейной области. Численное решение находится методом конечных элементов с помощью программы ANSYS. Доказано существование единой диаграммы нагружения в обобщенных координатах, с помощью которой определяется модуль упругости. Для подтверждения методики проведено экспериментальное измерение частот собственных колебаний цилиндрических образцов. Эти частоты сопоставлены затем с результатами полученными методом конечных элементов. Показано хорошее совпадение для найденного модуля упругост
Reach Improvement of Spectrum-Sliced Dense WDM-PON System
No full textIn this paper we successfully demonstrate the reach improvement of spectrum-sliced dense wavelength-division-multiplexed passive optical network (SS-DWDM PON) where amplified spontaneous emission (ASE) source is used as a seed light. Investigated optical system is built on the ITU-T DWDM frequency grid, defined in recommendation G.694.1 and therefore it is potentially much more compatible with other already existing WDM PON optical systems. In this way it is possible to replace the classic WDM PON system with our proposed extended-reach spectrum-sliced WDM PON system and reduce complexity of network architecture as well as cost per one user. The maximum reach of the spectrum-sliced dense wavelength-division-multiplexed passive optical network (SS-DWDM PON) system with data transmission speed 2.5 Gbit/s can be fairly limited by chromatic dispersion (CD) because of large optical bandwidth per channel compared to the bit rate. And therefore, dispersion degrades the performance of a SS-DWDM PON system more than it is observed in conventional laser-based system. This paper contains the investigation of high speed 8-channel spectrum-sliced DWDM PON system with efficient CD compensation methods like dispersion compensating fiber (DCF) and fiber Bragg grating (FBG). It is shown that CD compensation has an important role for guaranteed downstream optical link performance and maximum transmission line length of high speed SS-DWDM PON system. Results show that FBG used for CD compensation in high speed spectrum-sliced dense WDM PON systems provide better accumulated CD compensation and increase optical link length up to 150% while DCF fiber provides up to 130% reach improvement